An international, randomized, double-blind, placebo-controlled phase 3 trial of intramuscular alefacept in patients with chronic plaque psoriasis

Background: Alefacept, human lymphocyte function - associated antigen 3/immunoglobulin 1 fusion protein, binds to CD2 molecules on the surface of activated T cells, selectively targeting memory-effector (CD45RO⁺) T cells, which comprise more than 75% of T cells in psoriatic plaques. Objective: To examine the efficacy and tolerability of intramuscular alefacept. Design: International, randomized, double-blind, placebo-controlled, parallel-group trial. Patients: A total of 507 patients with chronic plaque psoriasis. Intervention: Placebo, 10 mg of alefacept, or 15 mg of alefacept administered once weekly for 12 weeks followed by 12 weeks of observation. Main Outcome Measure: Psoriasis Area Severity Index (PASI). Results: Alefacept treatment was associated with dose-related significant improvements in PASI from baseline. Throughout the study, a greater percentage of patients in the 15-mg group than in the placebo group achieved a significant reduction in PASI. Of patients in the 15-mg group who achieved at least 75% PASI reduction 2 weeks after the last dose, 71% maintained at least 50% improvement in PASI throughout the 12-week follow-up. There were no opportunistic infections and no cases of disease rebound. Conclusion: Intramuscular administration of alefacept was a well-tolerated and effective therapy for chronic plaque psoriasis and thus represents a convenient alternative to intravenous dosing.